Comprehensive changes including:
- Refactor picking slip line handling for multiple document types across print endpoints
- Add new `/api/v1/stock-purchases/picking-slip` API for stock booking picking slips
- Implement reusable Splitter component and useSplitRatio hook for resizable panels
- Add floating/fullscreen invoice viewer to collection confirm page
- Add real-time stock booking update event for invoicing tab
- Add full test coverage for all new components and APIs
- Include temporary chat attachment images for testing purposes